A conventional variable intake apparatus variably changes a length of an intake passage in accordance with rotation speed of an internal combustion engine to enhance a torque performance of the engine. Specifically, intake air is distributed to either a main passage, which accommodates a valve disc of the butterfly valve, or a bypass passage, through which intake air bypasses the butterfly valve, in a conventional variable intake apparatus, so that the length of the intake air passage is changed in the butterfly valve apparatus.
According to JP-U-61-6648 and JP-U-59-76731, a butterfly valve apparatus includes multiple valve discs, which are respectively supported by multiple valve shafts. The valve shafts are connected with each other, so that the valve discs can be integrally rotated. Furthermore, the valve shafts are connected with each other via spring pins and blade springs, so that thermal expansion arising in the valve shafts is absorbed. Thus, the valve discs can be restricted from causing a disorder.
However, in the structures of the JP-U-61-6648 and JP-U-59-76731, the spring pins and blade springs need to be assembled to the outer peripheries of adjacent valve shafts by hands in narrow spaces between adjacent valve discs. Therefore, time needed for connecting the valve shafts may increase, and total manufacturing time of the butterfly valve may increase.